Chapter 22

Question 1

Quality Assurance

Answer 1

is the routine, periodic evaluation of a system to guarantee optimal image quality
It is a medical and legal necessity

Question 2

Quality Assurance Requirements

Answer 2

Assessment of system components
Repairs
Preventative maintenance
Record keeping

Question 3

QA Goals

Answer 3

Proper operation of equipment
Detect gradual changes in performance
Minimize downtime
Reduce the # of non-diagnostic exams
Reduce the # of repeat exams

Question 4

QA Devices

Answer 4

Tissue equivalent phantom
Doppler phantom
Beam profile/slice thickness phantom

Question 5

QA is based on Objective Standards

Answer 5

Unbiased
Factual
Repeatable results; regardless of the tester

Question 6

Tissue Equivalent Phantom

Answer 6

Box filled with medium that has the same PS and attenuates, scatters, and presents echogenicities similar to soft tissue
-Embedded in the medium are strategically located pins (strings, rods), mock cysts and masses

Question 7

Doppler or Flow Phantoms

Answer 7

Used to evaluate Doppler systems
Modern include circulation pump which propels fluid through vessels embedded in a tissue equivalent phantom
-assess characteristics of all Doppler modalities including PW, CW, color, and power mode

Question 8

Slice Thickness Phantom

Answer 8

Used specifically to evaluate slice thickness which determines elevational resolution
-the display demonstrates the beam geometry or thickness

Question 9

Sensitivity

Answer 9

the ability of the system to register low level echoes

Question 10

Normal sensitivity

Answer 10

is the gain, TGC, and power setting where all pins, cysts and masses are accurately displayed
It is recorded and should not change from test to test

Question 11

Maximum Sensitivity

Answer 11

is evaluated by setting the power and amplification to maximum and determining the maximum depth of tissue like texture
This depth should not differ from one routine evaluation to the next

Question 12

Dead Zone

Answer 12

is the region close to the probe where images are absent due to the time it takes to switch from transmit to receive

Question 13

Registration Accuracy

Answer 13

is the ability of the system to place reflections in the proper positions

Question 14

Range or vertical depth calibration

Answer 14

describes the systems accuracy in placing reflectors at correct depths
-An error could indicate system malfunction or the PS in phantom fell off 1,540 m/s

Question 15

Horizontal calibration or registration accuracy

Answer 15

is the ability to place echoes in their correct position horizontally across the display (perpendicular to the sound beam)

Question 16

Distance Measurement Accuracy

Answer 16

The distance between two vertical and horizontal pins should be measured to check the digital calipers

Question 17

Focal Zone

Answer 17

The focus is adjusted (depth, #) and the lateral resolution assessed in the region effected

Question 18

Axial Resolution

Answer 18

is evaluated by scanning a set of closely spaced pins positioned front to back in the beam

Question 19

Lateral Resolution

Answer 19

is evaluated by scanning a set of closely spaced pins positioned side by side in the beam

Question 20

Compensation Operation or Uniformity:

Answer 20

Two same reflectors in phantom are located at different depths. TGCs are applied to ensure equal echodensities can be displayed

Question 21

Mock cysts and solid masses:

Answer 21

the tissue equivalent phantom is used to evaluate the dimension, texture, and fill-in of cysts

Question 22

Display, Hardcopy Output, and Grayscale dynamic range

Answer 22

Power, gain, compress are adjusted and grayscale change evaluated
Adjusting contrast and brightness only effects that monitor not stored or archived images

Question 23

Comparison Test

Answer 23

is the test you want to look at

Question 24

Sensitivity

Answer 24

the ability of the comparison test to detect disease
TP/ (TP + FN)

Question 25

Specificity

Answer 25

The ability of the comparison test to detect the absence of disease
TN/(TN + FP)

Question 26

Accuracy

Answer 26

the percentage of times the comparison test is right
(TP+TN) / (TP + FP + TN + FN)

Question 27

Positive Predictive Value

Answer 27

the % of time the test correctly predicted the presence of disease relative to the total number of time the test predicted disease
TP/(TP + FP)

Question 28

Negative Predictive Value

Answer 28

the % of time the test correctly predicted the absence of disease relative to the total number of times the test predicted no disease
TN/(TN + FN)